Effect of Peripheral Defocus on Axial Growth in Hyperopes

Hyperopia, also known as farsightedness, is a common type of refractive error where distant objects may be seen more clearly than objects that are near. Hyperopia is a known risk factor for amblyopia, (lazy eye), which may occur as a result of a squint (turn), or due to different levels of hyperopia between each eye (anisohyperopia). Hyperopia and anisohyperopia often persist into adulthood resulting in impairment to binocular vision. Current management involves prescribing spectacles or contact lenses to correct the hyperopia in each eye, usually as a lifelong intervention. In recent years there has been a great deal of interest in delaying progression of myopia (short-sightedness) by slowing down the growth of the eye using a particular type of contact lens termed a centre-distance multifocal design. There have been some encouraging results in this area to date. The proposed study here would explore the use of centre-near multifocal design contact lenses to encourage growth of the eye, thereby reducing hyperopia. There are three elements to the programme of research: 1. The natural progression of axial growth and refractive error will be measured in hyperopic and anisohyperopic subjects aged between 5 and 19. In other words, the natural growth of the eye will be followed without any intervention 2. As a paired eye control study anisohyperopes aged between 8 and 15 will be fitted with a centre-near multifocal design contact lens in their more hyperopic eye and a single vision contact lens in the fellow eye, if required. The progression of axial growth and refractive error will be measured and compared in each eye 3. Subjects' aged between 8 and 15 with similar levels of hyperopia in each eye will be fitted with centre-near multifocal design contact lenses in each eye. The progression of axial growth and refractive error will be measured and compared to subjects in the natural progression study